Air pump



I. L. NILSON AND I. PRINCE.

Am PUMP. APPLICATION FILED 1^N13, 1919.

1,404,470, Y Patengd Jan. 24, 1922'.

UNITED STATES PATENT OFFICE.

' K JoHNV L.v NILsoN AND JOHN PRINCE, or oHIoAG-OQILLINQIS.

AIR PUMP.

Specification of Letters Patent.

Patented Jan. 24, 1922.

Application led January 13, 1919. Serial No. 270,791.

. States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Air-Pumps, of which the following is a specification.

Our invention relates topump constructions and has particular reference to pistons for air pumps used for inflating automobile tires and the like. The object of our invention is to provide simple and effective means for maintaining the compression operativeness of the combination piston packing ring and air-inlet valve, or dished fiber disk, on pistons of this type. The

flange of said piston 'packing frequently becomes dry or set so that it fails to expand against the sides of the pump cylinder on the compression stroke, and the present improvement is designed to remedy this, and with said object in view our invention consists in the novel construction, combination and arrangement of parts hereinafter described in detail, illustrated in the accompanying drawing, and more particularly pointed out in the appended claims.

In the drawing- Figure l is a longitudinal section with ends broken away, of a usual form of air pump cylinder with our improved piston, the metal cup of which is shown in elevation.

Figure 2 is an enlarged section taken substantially on line X- of Figure l.

In the several views 2 represents the pump cylinder; 3, the dished or flanged piston; 4, the correspondingly shaped fiber 0r leather cover for same; 5, the disk between which and the piston 3 the valve and packing 4 is clamped; 6, the piston-rod or stem with a reduced and threaded end 7 which engages a central bore through the parts 3 and 4 and has a nut V8 which, when tightened draws the Parts 3V and 5 together on the part 4. The foregoing are the usual details lof construction. Y

The present improvement is operative to press a sufficient portion of the rim or flange 9- of the part 4 against the inner sides of the cylinder 2 to cause said rim or flange to expand, or .take hold under airpressure against said cylinder walls. For this purpose we provide a spring tension operating through slots or openings 10 to l5 in the flange 16- of the piston Through said openings air-pressure co-operates with the spring-tension on the forward stroke of the piston. We'have provided a simple and inexpensive spring tension in the form of a piece of spring-wire bent to form a series of loops or projections 17 to 22 which passithrough said slots 10 to l5 and bear against the flange 9 at a sufficient number of points to start the expansion of the whole flange against the cylinder sides. The spring pressure against the fiber flange tends to hasten such expansion even Vwhere the flange is normally operative, and we have found that the air-forcing capacity of the pump is very materially increased by this spring assistance. The spaces on the fiber flange that are between the spring-pressed points are sufficient to freely admit air between the flange and the cylinder, even when strong spring pressure is applied at said points, on the backwardor air-intake, stroke of the piston.

Obviously the embodiments of our inven` tion may be varied in numerous ways with` out departingfrom the spirit thereof. The present embodiment, however, is particularly adapted for existing constructions of air pumps with the slight change of making the openings, or their equivalents, in the piston flange.

Having thus described our invention, we claim as new and desire to secure by Letters Patent- 1. The combination with an air cylinder and a flanged piston therefor having apertures through its flange, of a flanged flexible cover of corresponding form which serves as an air inlet valve and means o ratin through the piston flange for eXpan ing sai cover against said cylinder.

2. The combination with an air-pump cylinder, of a piston, a flexible .air inlet valve packing between said cylinder and piston,

. and a spring-wire having outward bends n inder and -a piston therefor having a lperforated flange which provides fa hollow space therein, andan' pressure openings therefrom, Yo1 @flexible air inlet valve and piston portion partly interposed between said piston andsaid cylinder, and tension de- 10 vices on said piston bearing aga-inst said inlet valve and piston portion.

In testimony whereof We have hereunto signed our names. Y p J OHN L. NILSON. f 'JOHNz PRINCE. 

